Among conventional heating cookers is one which blows out steam through a ceiling surface and left-and-right side faces of a cooking chamber in order to achieve a cooking free from heating unevenness (see, e.g., JP 2005-344967 A). This heating cooker includes a steam temperature-raising device placed on an upper surface of the cooking chamber so that steam derived from the steam temperature-raising device is supplied to the cooking chamber via a ceiling steam outlet while the steam from the steam temperature-raising device is supplied from the left-and-right side-face outlets via steam supply passages.
However, the heating cooker has a problem that the steam supply passages from the steam temperature-raising device to the side-face outlets, which are bent from ceiling surface to side face side, are complex in structure and higher in parts cost, as well as longer in assembling time, leading to increases in its manufacturing cost.